I am in a 9:00 team in the lounge. What time does a challenge start in the lounge?

Regular team competitions usually start 14 hrs (occasionally 16 hrs) before the club's meeting time. So that's 7:00pm the night before if your meeting is at 9:00am. Or 7:00am if your meeting is 9:00pm.

BTW, challenges refer to Detective Needed Challenges where you earn keys for prizes and start at a designated time (i.e. 10am) for each time zone.